Preloaded vials and syringes filled with various fluid medicines (herein after “medicaments”) have become part of the ordinary procedure for treatment of various maladies and illnesses in the developed world. Whereas in previous generations, medical personnel introduced intramuscular or intravenous medications by filling a graduated syringe through a needle from a fluid medicament bottle by displacing a piston plunger manually to a desired volume. Any air gap between the plunger and the fluid medication was carefully expelled and the injection delivered to the patient. In the modern world, these methods have now been occasionally replaced largely with automated equipment including infusion apparatus which accepts preloaded cartridges or syringes having the fluid medicaments hermetically sealed therein. The prior use of manual syringes and a trained individual to inject a patient allowed the medical specialist to expel from the syringe any air or gaseous bubbles possibly present in the syringe. It is well known that intravenous introduction of any such gas or bubbles may cause an embolism which is typically deleterious to the patient. Automated systems now produce a medicinal cartridge having a resilient stopper therein which preferably does not have any gaseous component between the stopper and the fluid medicament. Such gaseous material and the gap defined by thereby is known in the art as “headspace.” In addition to the possibility of embolism, such gas may not be inert, such as conventional atmospheric gas which may include contaminants including microorganism possibly causing deleterious positive bacterial growth within the medicament. Such headspace may also cause dosing errors in customized infusion equipment. Efforts to automate the process of filling such fluid cartridges and vials and stoppering the same have made significant progess. The most successful such processes is the so called vacuum stoppering of syringes. As used herein, the terms “fluid container,” “fluid cartridge,” fluid syringe,” “syringe vial,” and the like are interchangeable. Furthermore, the terms “stopper”, “piston” and “plunger” may be used interchangeably as is the custom in the industry. Under this method, a syringe filled with a medicament or plurality thereof are placed into a multi-cartridge vacuum chamber and a resilient, deformable stopper is placed onto an open upper end of the vial under a partial vacuum. Once the stoppers are appropriately positioned at least partially in engagement with an open throat of the syringes/cartridges the partial vacuum is released and the chamber in which the cartridges reside is vented to atmospheric pressure. Thereupon the stoppers are urged by the differential pressure thereon to enter fully into the cartridges, sealing the same. U.S. Pat. No. 7,328,549 Kinney et al. discloses a process for septic vacuum tilling and stoppering of low viscosity liquids in syringes applying such a vacuum method. Kinney et al. go to great lengths to prevent transition of the liquid medicament to the gaseous phase by suppressing the vapor pressure of the liquid by significantly lowering the temperature thereof during the vacuum stoppering process. Kinney et al. show that doing so substantially reduces the headspace between the medicament and the resilient stopper. Nevertheless, the inventors herein have discovered that the process disclosed by Kinney et al. and others does not position the stopper with sufficient axial accuracy to prevent a gap being formed between the fluid medicament and the stopper. As a result, the fluid medicament can overtime enter the vapor phase creating the undesirable so called headspace.
Other prior art processes for inserting a resilient stopper into medicament cartridges rely on mechanic insertion of the stopper into the cartridge resulting in permanent deformation of the outer side walls of the stopper such as to compromise the desired hermetic seal between the stopper and the cartridge container. The cartridges themselves are typically manufactured from a type of plastic such as polyolefin polymer while the stoppers are typically manufactured from a medical grade silicon coated with a polytetrafluoroethylene (PTFE) low friction coating. In one mechanical prior art technique the cartridges are arranged in an array in a tray inside a vacuum chamber. Individual tubes having an outer diameter smaller than the inner diameter throats on the cartridges are positioned above the open cartridge throats and the tubes are preloaded with the silicon stoppers. The outer diameter of the stopper is significantly radially smaller than the inner diameter of the tubes thus the stoppers are substantially radially deformed while in the tubes. While the chamber is partially evacuated, pistons depress the stopper into the tube which has previously been lowered into position within the cartridges. The stopper emerges from the free end of the tube inside the cartridge where upon the deforming force of the tube has been released and the stopper radially expands to fill the throat of the cartridge. Thus, the stopper has been disadvantageously deformed as specifically the PTFE coating has been deformed beyond its elastic threshold such that upon re-expansion inside the cartridge, the stopper typically wrinkles or other permanent deformities remain. These deformities compromise the hermetic seal, and through capillary action can draw the fluid medicament back out of the cartridge beyond the stopper over time. As a result, the fluid dosage of the cartridge is no longer correct, or the Inverse occurs and ambient atmosphere is drawn into the cartridge.
Thus, a need exists for a method and apparatus which can accurately position elastomeric stoppers into fluid cartridges repeatedly and precisely to a final selected depth. A further need exists to prevent radial deformation of the stopper beyond an elastic deformation limit of a coating on the stopper such that the hermetic seal of the stopper with respect to the container or cartridge is not compromised.